html,body{
    margin: 0;
    padding: 0;
}
div{
    /* background-color: chartreuse; */
    /* width: 500px;
    height: 400px; */
    /* min-width: 500px;
    min-height: 500px;
    max-width: 900px;
    max-height: 900px; */
}

#a{
    background: silver;
    width: 200px;
    height: 200px;
    margin: 52px;
}

#b{
    background: gray;
    height: 80%;
    width: 80%;
    border: 10px solid #000;
    /* padding: 5px; */
    /* padding-left: 25px;
    padding-top: 15px; */
    /* padding: 10px 0px 0px 20px; */
   /*  padding: 10px 20px; */
}

#c{
    width: 500px;
    height: 400px;
    background: silver;
    /* overflow: hidden; */
    /* overflow: auto; */
    overflow: scroll;
}